No, it’s nationwide, all carriers and mvnos are signed on to the US Block Status since IMEI became standard. It’s a separate list from the global GSMA and not all carriers in the US report to the GSMA like they should,but if a device is reported lost or stolen in the US it cannot be activated by a US carrier until resolved.
No, they are not. Blacklists are per carrier, at least when dealing with American primary carriers, and not MVNOs.
No, it’s nationwide, all carriers and mvnos are signed on to the US Block Status since IMEI became standard. It’s a separate list from the global GSMA and not all carriers in the US report to the GSMA like they should,but if a device is reported lost or stolen in the US it cannot be activated by a US carrier until resolved.
Except I have used unlocked IMEI blacklisted devices on different carriers, so if one exists in theory, it doesn’t appear to be there in practice.